In her first tournament since her run to the fourth round of Wimbledon, it appeared Laura Robson's stay at the Southern California Open would be a short one, as she found herself down to Ayumi Morita, 64 54, 30-0, in first round play on Tuesday.

But the WTA's highest ranked teen turned it on from there, overpowering Morita in losing only two more games en route to a 46 75 62 triumph that lasted 20 minutes short of three hours.

The competition gets much stiffer in the next round for World No.32 Robson, as she takes on World No.7 Petra Kvitova. However, the Brit is unlikely to be intimidated, having edged Kvitova in three sets in the second round of the Australian Open in January in their only previous meeting.

US Open: Ruthless Laura Robson is going in one direction• Laura Robson hoping to better 2012 US Open performance• New coach Miles Maclagan has developed her net game

Laura Robson, a teenager until the second Monday of the Australian Open in January, might long ago have shed her innocence in the hard-headed world of the tennis Tour but she remains as beguiling as a drop shot.

Quick to giggle, slow to frown but always ready for business, Britain's best woman player treats jousting with journalists as entertainment. She probably suspects some of us have no idea who One Direction are, for instance, but she shares her anecdotes nonetheless, even though she knows we'd be more comfortable discussing Lourdes Dominguez Lino, her experienced Spanish opponent in the first round of the US Open, which starts on Monday.

"I've had a couple of random looks just, like, walking around Manhattan," Robson said of the reception she has had since returning to the scene of her brilliance at Flushing Meadows a year ago, when she reached the fourth round and sent Kim Clijsters into retirement a loser, then beat Li Na for good measure.

"They must be British tourists, I would say. Yeah, in New York they don't really say 'Hi', they just stare, which is a bit awkward. We were walking past the queue for the One Direction concert that they had this morning, and there must have been a couple of hundred girls camped out. Some of them had been there for five days already … I'm not sure where their parents are. Yes, like, a couple of them are, like, "Oh my God, you're the one that Harry* tweeted!' So, yeah, I don't think they know my name or anything, it's just, like, that's how they know..." (*Styles, oldster).

The contrast with Sloane Stephens, the ultra-serious American less than a year older than her and with whom she might one day forge a substantial rivalry, is striking. Robson can be sharp too, no question (her sarcasm is as sharp as Maria Sharapova's), but her inclination is to keep it light, on the court and off. It is almost certainly why she split with the Croatian disciplinarian Zeljko Krajan after nine months, before taking up with Andy Murray's former coach, Miles Maclagan, in May.

"I understand what he wants to work on," she said. "We have the same ideas of how I want to play and what I need to improve. He's a very laid back guy anyway, and I think I am a fairly laid back person, so it works well. When you understand what he wants to be working on, it's a lot easier to give everything. Before I was feeling that it wasn't gelling in the same way."

How, exactly? "How I want to play on the match court. I don't want to be someone who just hits the ball 100% every time. You can play with freedom and still mix up the pace, mix up the spins and everything – and that's what I want to be doing. You get into that very one-dimensional kind of tennis if you don't work on slicing and coming in, and all that stuff. Miles has had a lot of experience in doubles as well. I haven't been able to use this hand [her injured right] for the last couple of weeks, which gave us a good reason to work on volleys and slices. I think it's gone well. I do feel good at the net, and I've also played a fair bit of doubles, much more than I have in the past, over the last couple of months. In general I feel more comfortable coming in, which is definitely a good addition to my singles game."

This is revealing on two counts: her right wrist until recently has been decommissioned, although she is happy with her preparation, and this noted two-fisted, baseline belter is now open to playing a more expansive, and risky, game. If it works, she might not only do well here, but in the rankings, where she resides at 32 in the world, although she is not bothered about having snuck inside the seedings limit for the US Open.

"I'm seeded, yes, but I think it only makes a difference when you're top 16. Like, top 32, that's borderline."

Doesn't it parlay into having an easier time at the tournament? "On my badge, I'm still parking lot E or F. Not quite the same as parking lot A." And the difference? "It's close to the locker rooms, which is helpful rather than walking 20 minutes."

Once, in that inner sanctum, Laura is still Laura. "I'm just a bit more recognised by other people," she conceded, "but someone took my locker. The previous winners have their names on their lockers so you know not to take theirs. I got here quite early so I thought I would be safe because I am in the back — but a qualifier took it. Now I am at the bottom and people keep putting their bags in front of my locker so I have to keep moving everything around. I'm hoping whoever it is doesn't qualify so I can take it back."

That is Robson at her most lighthearted, encouraging the hope that she will take that carefree attitude into the tournament to give full expression to her strengths. However, just as she did not have to think long before ditching Krajan, so she was quick to make changes in her management team. In July, Robson took on a new agent, Max Eisenbud, who also looks after Sharapova and Li on behalf of the International Management Group, once the most powerful agency in sport and still influential, despite parting with Roger Federer and Rafael Nadal in recent years.

"He basically harassed me for, like, a good two years," she chided Eisenbud, who was sitting at the back of the interview room. "Abi [Tordoff, her long-time agent] and I are still great friends. I've known her since I was eight or nine so she's always going to be part of the family, basically, and I just thought it was time for a change in the business area."

Ruthlessness is not a word often associated with Laura Robson. Maybe it should be. For the better.